diff --git a/src/client.ts b/src/client.ts
index a05c4dd..0e249a2 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -291,8 +291,12 @@ export class PlatformClient {
     /**
      * Sends a report_progress event to update the PR title and/or description.
      * This triggers the platform to update the pull request associated with the job.
+     *
+     * `commitSha` is the SHA of the commit pushed alongside this update, when known.
+     * Omitted keys are left out of the payload entirely, so servers that do not
+     * understand a field are unaffected.
      */
-    async sendReportProgress(options: { prTitle?: string; prDescription?: string }): Promise<SendResult> {
+    async sendReportProgress(options: { prTitle?: string; prDescription?: string; commitSha?: string }): Promise<SendResult> {
         const url = new URL(`jobs/${this._jobId}/progress`, this.baseUrl);
         const contentObj: Record<string, string> = {};
         if (options.prTitle !== undefined) {
@@ -301,6 +305,9 @@ export class PlatformClient {
         if (options.prDescription !== undefined) {
             contentObj.pr_description = options.prDescription;
         }
+        if (options.commitSha !== undefined) {
+            contentObj.commit_sha = options.commitSha;
+        }
         const payload: ProgressPayload = {
             namespace: this.namespace,
             kind: "report_progress",
diff --git a/src/git.ts b/src/git.ts
index 0c3f709..345882e 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -101,6 +101,12 @@ export interface CommitAndPushResult {
     hadChanges: boolean;
     /** Human-readable message describing the outcome */
     message: string;
+    /**
+     * SHA of the commit at HEAD after the push succeeded.
+     * Undefined if the SHA could not be resolved; a successful push is never
+     * reported as a failure just because this lookup did not work.
+     */
+    commitSha?: string;
 }
 
 // =============================================================================
@@ -301,12 +307,27 @@ export function commitAndPush(repoLocation: string, commitMessage: string): Comm
 
     pushWithRebaseFallback(repoLocation);
 
+    // Resolved only after the push succeeded, so the SHA always refers to a commit
+    // that is actually on the remote. Deliberately isolated in its own try/catch:
+    // a rev-parse failure must never turn an already-successful push into a
+    // reported error, which callers could retry into a duplicate commit.
+    let commitSha: string | undefined;
+    try {
+        commitSha = git(["rev-parse", "HEAD"], repoLocation).trim();
+    } catch (error) {
+        const msg = error instanceof Error ? error.message : String(error);
+        // Note: stderr, not stdout — commitAndPush runs inside the stdio MCP
+        // server (src/mcp-server.ts) where stdout is reserved for the MCP protocol.
+        console.error(`[Engine SDK] Push succeeded but resolving the commit SHA failed - ${msg}`);
+    }
+
     return {
         success: true,
         hadChanges,
         message: hadChanges
             ? `Committed and pushed: ${commitMessage}`
             : "No changes to commit. Pushed existing commits.",
+        commitSha,
     };
 }
 
diff --git a/src/mcp-server.ts b/src/mcp-server.ts
index d2967c9..c8c087d 100644
--- a/src/mcp-server.ts
+++ b/src/mcp-server.ts
@@ -116,6 +116,9 @@ async function executeReportProgress(
     const { commitMessage, prDescription } = input;
     const results: string[] = [];
     let hasError = false;
+    // Stays undefined unless a push actually happened and the SHA was resolved,
+    // so the local-only and error paths never report a SHA that is not on the remote.
+    let pushedCommitSha: string | undefined;
 
     log("executeReportProgress", { commitMessage, prDescriptionLength: prDescription.length });
 
@@ -125,6 +128,7 @@ async function executeReportProgress(
             const gitResult = commitAndPush(config.workingDir, commitMessage);
             log("git commit and push", { hadChanges: gitResult.hadChanges, message: gitResult.message });
             results.push(gitResult.message);
+            pushedCommitSha = gitResult.commitSha;
         } else {
             // Local-only mode: just stage and commit without pushing
             const { execFileSync } = await import("child_process");
@@ -160,6 +164,7 @@ async function executeReportProgress(
         try {
             const sendResult = await config.platformClient.sendReportProgress({
                 prDescription,
+                commitSha: pushedCommitSha,
             });
             if (sendResult.success) {
                 log("sent report_progress to platform");